MG-GIMP supports the following filetypes:

XCF
The native format for GIMP image files. In addition to uncompressed files with the .xcf extension, MG-GIMP accepts compressed versions that have one of the extensions .xcfgz, .xcfbz2, .xcf.gz, and .xcf.bz2 .

SVG

MG-GIMP currently provides support for scalable vector graphics files that use the .svg extension, though Mediagoblin is expected to support SVGs natively in the near future.

Palette

GIMP palette files use the .gpl extension and contain a color map with optional names for each of the colors.

Gradient

GIMP gradient files use the .ggr extension and contain a textual description of a GIMP gradient.

Pattern

GIMP pattern files are basically image files with some additional metadata attached. They use the .pat extension.

Curve

A GIMP curve file is a text file describing a spline curve used by the GIMP Curves Tool. While GIMP has never assigned a particular extension to curve files, MG-GIMP requires that they use the .curve extension.

Parametric Brush

GIMP parametric brush files use the .vbr extension and contain a textual description of a simple grayscale brush shape.

Brush

GIMP brush files are basically image files with some additional metadata attached and special interpretation of their colorspace and alpha channel. They use the .gbr extension.

Image Hose

GIMP image hoses (AKA pipe brushes) are animated brush files that contain within them a multilayer array of of images and some associated metadata. Image hose files use the .gih extension.

Dynamics

GIMP brush dynamics are plain text files that contain mappings and spline curves associating various input controls (pressure, tilt, etc) to brush parameters (opacity, size, angle, etc). GIMP brush dynamics files use the .gdyn extension.

Tool Preset

GIMP tool preset files are plain text files that contain a set of tool options for a GIMP tool. GIMP tool preset files use the .gtp extension.